[gmx-users] TIP4P water shrinks during energy minimization

[Valentin Gogonea]

Dear GMX Users:

I am trying to perform energy minimization on a box of TIP4P water with 
a small organic molecule using OPLS force field. When I use the option 
-DFLEXIBLE the water seems to shrink and I get high forces. I used both 
"steep" and "l-bfgs" minimizers and got the same behavior. With "cg" 
minimizer the optimization crashes giving  "nan" for coordinates.

I may do something wrong here and I wonder if any of you experienced 
this.

I included here the mdp file and a picture of the "optimized" box.

Thank you for your help.

Valentin


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